Generally, the industry of semiconductor manufacturing involves highly complex techniques for fabricating integrating circuits using semiconductor materials, which are layered and patterned onto a substrate, such as silicon. An integrated circuit is typically fabricated from a plurality of reticles. Generation of reticles and subsequent optical inspection of such reticles have become standard steps in the production of semiconductors. Initially, circuit designers provide circuit pattern data, which describes a particular integrated circuit (IC) design, to a reticle production system, or reticle writer.
Due to the large scale of circuit integration and the decreasing size of semiconductor devices, the reticles and fabricated devices have become increasingly sensitive to defects. That is, defects which cause faults in the device are becoming increasingly smaller. The device can generally be required to be fault free prior to shipment to the end users or customers.
Various inspection and metrology systems are used within the semiconductor industry to detect defects or characterize structures on a semiconductor reticle or wafer. One type of tool is an optical inspection or metrology system. In optical inspection and metrology systems, one or more incident beams are directed towards the semiconductor wafer or reticle and a reflected and/or scattered beam is then detected. The detected beam is used to then generate a detected electrical signal or an image, and such signal or image is then analyzed to determine whether defects are present on the wafer or reticle or characterize features on the sample under test.
Various light source mechanisms can be used with optical inspection and metrology tools. One example is an arc lamp based light source. Another example is a laser sustained plasma light source. Both an arc lamp and plasma based light source tend to produce a significant amount of out-of-band radiation, which leads to poor power conversion efficiency. Additionally, these light sources require complex thermal heat management mechanisms for the out-of-band radiation. The plasma based light source also has limits on power brightness scalability.
There is a continuing need for improved light sources for optical inspection and metrology tools.